IR-A% denotes the percentage of inherited runners who come around to score against a relief pitcher. It is determined by dividing the inherited runs scored against a pitcher by the total number of runners he has inherited. This statistic essentially asks the question: How often does a relief pitcher allow a runner (or multiple runners) to score when he enters the game with a runner (or multiple runners) on base?
Any baserunners allowed by a relief pitcher do not factor into his eventual IR-A percentage. Therefore, IR-A percentage has no bearing on a reliever's ERA.
In A Call
"inherited-run rate," "inherited-run-scored rate," "strand rate" (opposite)